From Websters 1828 Dictionary (link)

Lugubrious LUGU'BRIOUS, a. [L. lugubris, from lugeo, to weep.]
Mournful; indicating sorrow; as a lugubrious look.

From WordNet (r) 2.1 (2005) (link)

  lugubrious
      adj 1: excessively mournful

From Merriam-Webster's Collegiate Dictionary, 11th Edition (2003) (link)

  lugubrious adjective
   Etymology: Latin lugubris, from lugēre to mourn; akin
   to Greek lygros mournful Date: 1585 1.  mournful;
   especially  exaggeratedly or affectedly mournful  <dark, dramatic
   and lugubrious brooding — V. S. Pritchett> 2.  dismal
   <a lugubrious landscape> • lugubriously adverb
   • lugubriousness noun
  
  

From Oxford English Reference Dictionary (link)

lugubrious
adj. doleful, mournful, dismal.
Derivatives:
lugubriously adv. lugubriousness n.
Etymology: L lugubris f. lugere mourn

From Collins COBUILD Advanced Learner's English Dictionary (link)

  lugubrious
    If you say that someone or something is lugubrious, you mean that they are sad rather
    than lively or cheerful. (LITERARY)
    ...a tall, thin man with a long and lugubrious face...
    He plays some passages so slowly that they become lugubrious.
   = melancholy
   ADJ
   • lugubriously
    The dog gazed at us lugubriously for a few minutes.
   ADV: ADV with v, ADV adj
  
  
  

From English Explanatory Dictionary (link)

  lugubrious
  lu:ˈɡu:brɪəs adj. doleful, mournful, dismal. øølugubriously
  adv. lugubriousness n. [L lugubris f. lugere mourn]
  
  
  

From Webster's Revised Unabridged Dictionary (1913) (link)

  Lugubrious \Lu*gu"bri*ous\, a. [L. lugubris, fr. lugere to
     mourn; cf. Gr. ? sad, Skr. ruj to break.]
     Mournful; indicating sorrow, often ridiculously or feignedly;
     doleful; woful; pitiable; as, a whining tone and a lugubrious
     look.
  
           Crossbones, scythes, hourglasses, and other lugubrious
           emblems of mortality.                    --Hawthorne.
     -- Lu*gu"bri*ous*ly, adv. -- Lu*gu"bri*ous*ness, n.

From Soule's Dictionary of English Synonyms (link)

  lugubrious
  a.
   Mournful, sorrowful, doleful, sad, gloomy, melancholy, complaining.
  
  
  

From Moby Thesaurus II by Grady Ward, 1.0 (link)

  38 Moby Thesaurus words for "lugubrious":
     aggrieved, anguished, black, bleak, careworn, cheerless,
     depressant, depressing, dismal, dispiriting, doleful, dolorous,
     dour, dreary, dumb with grief, glum, grief-stricken, griefful,
     grieved, grievous, in grief, joyless, lamentable, morose, mournful,
     oppressive, plaintive, plangent, plunged in grief, rueful,
     saturnine, somber, sorrowed, sorrowful, sorrowing, sullen, tearful,
     woeful